1. Field of the Invention
This invention relates to a pull cord mechanism for self-opening umbrella, especially the type has five folds.
2. Description of the Prior Art
The umbrella has been one of indispensable tools in human daily life. Most people are fond of the foldable umbrella, because it is convenient to carry with in the folded form and is capable of keeping away both rain and sunshine effectively. The unique inconvenience is that the user has to withstand getting wet in the heavy rain while boarding on the cars or buses and closing the umbrella by hands.
For this weakness, a self-opening foldable umbrella has been invented, mainly comprising an upper sheave and a lower sheave fixed on the lower shaft with the pull cord winding on the sheaves. Because the pull cord is arranged very closely, when drawing the pull cord, a friction occurs which not only adversely affects the opening operation, but also shortens the life span of the pull cord.
For these defects noticeable on the prior art, an improvement is seriously required.
The inventor has dedicated great efforts for years to studying and improving these defects and come up with a novel pull cord mechanism as provided in this invention to eliminate the defects mentioned above.
The major object of this invention is to provide a shorter center shaft on which the pull cord mechanism for self-opening umbrella is mounted. Another object of this invention is to stagger the winding arrangement of the pull cord in an effort to evade the cord friction and make the self-opening at ease.
Another object of this invention is to determine the volume of the folded umbrella by means of the number of sheaves applied.
Another object of this invention is to provide a pull cord mechanism for the self-opening umbrella with simplified structure, pragmatic application and easy assembly.
To achieve the foregoing objects, the pull cord mechanism for the self-opening umbrella constitutes at least a core tube rest, a core tube, a plurality of sheaves, a lower shaft, a center shaft and a string of pull cord, in which center shaft contains several sections of short shaft for retractility. The core tube rest provides a rack to support perpendicularly the first and second sheaves. The core tube is fastened at the bottom of the core tube rest and links to the first sheave. The core tube rest sits on the top of the center shaft; the core tube stays in the hollow of the center shaft and a cord retainer perch at the bottom end of the center shaft. The lower shaft is sleeved on the center shaft which is allowed to slide up and down within the lower shaft. The third and fourth sheaves are arranged in parallel on the side of the lower shaft. One end of the pull cord is fixed on the core tube rest or the upper shaft, the other end of pull cord will go winding the first sheave, then passing the third sheave on the lower shaft, back to the second sheave on the core tube rest and finally coming to the fourth sheave on the lower shaft. The first and second sheaves are vertically arranged and the third and fourth sheaves are in parallel. This winding disposition always keeps the pull cord among the sheaves apart at a fixed clearance, so they will move smoothly with no entanglement and abrasion.